Pneumatic tool lubricant



United States Patent PNEUMATIC TOOL LUBRICANT Mel in E. Gililland, Richard C. Massin, Port Arthur, Tex., a corporation of Delaware Claims. (Cl. 252--33.4)

Givens, and Hyman D. assignors to Texaco Inc,

This invention relates to an improved lubricant for pneumatic tools, and more particularly to a lubricating composition having superior lubricating properties which are obtained by means of an additive combination includ ing a petrolatum oxidate, sulfur and an alkali metal sulfonate.

Lubricants employed for the lubrication of pneumatic tools, such as rock drills, are required to have a special combination of properties including non-corrosiveness to copper, good extreme pressure properties in order to protect the tool parts from excessive wear due to high rotational loading, including shock loading, and very superior rust preventiveness to protect the tool parts from rusting under the conditions encountered in drilling operations. Since these lubricants often become contaminated with considerable quantities of water in service, particularly in wet drilling operations, they must have the property of emulsifying readily with water in order to resist being washed away from the lubricated parts.

One type of pneumatic tool lubricants that has been employed commercially has been a compounded mineral oil containing about 10 percent blown rapeseed oil. Because of the expense of blown rapeseed oil, compositions of this type have been excessively expensive for non-recirculating lubrication of pneumatic tools. Pneumatic tool lubricants based on blown rapeseed oil have the further disadvantage of having a pronounced odor which is particularly objectionable when the lubricant is employed in small enclosed areas. The commonly assigned Bright and Hall Patent 2,734,868 discloses improved pneumatic tool lubricants comprising lubricating oil base containing a special combination of additives comprising a phosphorus acid ester such as tricresyl phosphate, a sulfurized fatty oil such as sulfurized lard oil, a phosphatide emulsifying agent and a polymeric stringiness agent such as a polymerized olefin. The petrolatum oxidate-, sulfur, and alkali metal sulfonate-containing lubricants of this invention possess better extreme pressure, anti-rust and emulsification properties than the lubricants disclosed in the Bright and Hall patent.

The improved pneumatic tool lubricant of this invention comprises a mineral lubricating oil, 0.1 to 1 percent sulfur, 2 to 8 weight percent petrolatum oxidate and 0.1 to 0.8 weight percent alkali metal sulfonate. The mixture of mineral lubricating oil, petrolatum oxidate and sulfur is blended into a homogeneous mixture by heating at a temperature between 250 and 350 F. The pneumatic tool lubricant also advantageously contains minor amounts of a high molecular. weight polymeric stringiness agent and of a mercaptobenzothiazole corrosion inhibitor.

The mineral lubricating oil employed as the base oil in the above compositions is preferably a naphthenic or mixed naphthenic and parafiinic refined oil having a viscosity in the range of from about 100 to about 900 seconds Saybolt Universal at 100 F., although somewhat lower or higher viscosities may be employed to obtain lubricating compositions adapted for unusual operating conditions. Ordinarily, an oil having a viscosity in the range of from about 300 to about 700 seconds Saybolt Universal at 100 F. is most suitably employed.

The mineral lubricating base oil usually comprises to 98 percent of the pneumatic tool lubricant. It has been found that a base oil concentration between about 92 and 96 percent is normally used in the formulation of the lubricants of this invention.

The petrolatum oxidates which impart the desired emulsification properties to the pneumatic tool lubricants of this invention are obtained by catalytic air oxidation of petrolatum at temperatures between 270 and 400 F. and at a pressure below 20 pounds per square inch gauge. Under these conditions there are formed high ester content oxidates characterized by Neut. No. to Sap. No. ratios below about 0.25. Petrolatum oxidates are either of the low viscosity type or the high viscosity type depending upon the air feed rate employed during the catalytic air oxidation.

The preparation of high viscosity petrolatum oxidates, the preferred oxidates for the formulation of the pneu matic tool lubricants of the invention, is described in detail in the commonly assigned J. K. McKinley, G. S. Bright and R. F. Nelson Patent 2,705,241 and involves air oxidation at an air feed rate of 10 to 35 standard cubic feet of air per pound of petrolatum per hour in conjunction with the use of a temperature between 270 and 400 F. and at a pressure below 20 p.s.i.g. The high viscosity petrolatum oxidates are characterized by a Neut. No. to Sap. No. ratio below 0.25 and by an SUS viscosity at 210 F. above about 1500. Typical high viscosity petrolatum oxidates have a maximum Neut. No. of about 35, a Sap. No. between 90 and 145, an unsaponifiable content between about 40 and 60 percent and an SUS viscosity at 210 F. between 4,000 and 12,000.

The preparation of the low viscosity petrolatum oxidates is described in the copending commonly assigned J. K. McKin'ey, G. S. Bright and R. F. Nelson application, Serial No. 537,893, filed September 30, 1955, now U.S. Patent 2,818,419, and involves catalytic air oxidation of petrolatum at an air feed rate of 2 to 10 standard cubic feet of air per pound of petrolatum per hour in conjunction with the use of a temperature between 270 and 400 F. and a pressure below 20 p.s.i.g. The low viscosity petrolatum oxidates are characterized by a Neut. No. to Sap. No. ratio below about 0.2 and an SUS viscosity at 210 F. below about 700. Typical low viscosity petrolatum oxidates have a maximum Neut. No. of 20, a Sap. No. between about 60 and 100, an unsaponifiable content between 40 and 60 and an SUS viscosity at 210 F. between 400 and 700.

The petrolatum oxidates employed in the pneumatic tool lubricants of this invention are readily soluble in mineral lubricating oils. The improved properties of the petrolatum oxidate employed in the lubricants of this invention are apparently attributable to their high ester content since this characteristic differentiates the petrolatum oxidates from paraffin Wax oxidates employed heretofore in the formulation of lubricating compositions.

The concentration of petrolatum oxidate required for obtaining the desired rust protection, extreme pressureand emulsification properties in the pneumatic tool lubricants of the invention falls between 2 and 8 weight percent. Formulations containing between 3 and 6 weight percent petrolatum oxidate have proven particularly effective in field service.

The sulfur component of the penumatic tool lubricants of the invention is present in a concentration between 0.1 and 1.0 weight percent of the total lubricant. Sulfur concentrations within the prescribed range impart the desired extreme pressure and anti-wear properties to the pneumatic tool lubricants. A preferred sulfur concentration is in the range of 0.3 to 0.7 Weight percent.

The petrolatum oxidate and sulfur are blended into i the mineral oil base by a simple procedure involving raising the temperature of the mineral oil base to 250 to 350 F. and adding the sulfur and petrolatum oxidate. No particular sequence of addition of the components is necessary for the homogenization of the petrolatum oxidate with the sulfur and mineral oil but a minimum heating period of about /2 hour is necessary.

The preferred procedure for homogenization of the sulfur and petrolatum oxidate into the mineral oil base involves adding the mercaptobenzothiazole corrosion inhibitor to the mineral oil, heating the mineral oil to about 300 F. with stirring, adding the prescribed amount of sulfur, maintaining the stirred mixture at about 300 F. for about 30 minutes and adding the petrolatum oxidate and subsequently cooling the mixture. During the stirred cooling of the mixture the alkali metal sulfonate, the high molecular weight polymeric stringiness agent and the anti-foam agent are added.

An alternate procedure for incorporating sulfur into the pneumatic tool lubricants of the invention involves separate preparation of a petrolatum oxidate-sulfur concentrate. In this procedure petrolatum oxidate is reacted with 4 to weight percent sulfur at a temperature between about 300 and 350 F. for a period between 1 /2 and 4 hours. The sulfurized oxidate is then dissolved in a light naphthene base oil to form a concentrate comprising percent sulfurized oxidate. The concentrate is cooled, settled, filtered and subsequently blended with mineral oil to give a lubricant composition containing the prescribed amounts of sulfur, petrolatum oxidate and mineral oil. This procedure is normally not employed because it requires a long r period of time for homogenization of the sulfur than the preferred procedure described above.

The alkali metal sulfonate component, which improves the emulsification properties of the lubricant, constitutes 0.1 to 0.8 weight percent of the total lubricant with concentrations between 0.2 and 0.6 weight percent normally being employed. The alkali metal sulfonate is normally derived from a petroleum sulfonic acid which is produced by the reaction of concentrated sulfuric acid with a mineral lubricating oil fraction. Alkali metal salts of alkaryl sulfonic acids such as C alkyl benzene sulfonic acid and dinonyl benzene sulfonic acid may also be used to improve the emulsification properties. Even though sodium petroleum sulfonate is normally used because of its availability and lower cost, other alkali metal sulfonates, such as sodium dinonyl benzene sulfonate, potassium petroleum sulfonate and lithium petroleum sulfonate may be used.

The high molecular wei ht polymeric stringiness agent may be a polymerized olefin or a polymerized oxygencontaining material such as polymers of vinyl ethers or polyesters of substituted fatty acids. Isobutylene polymer havinga Saybolt Furol viscosity at 210 F. of about 1,000 to 2.000 seconds is particularly suitable for this purpose. Such pol meric material may be employed in amounts ranging from about 0.1 to about 3.0 percent by weight of the composition.

The desired anti-corrosive properties, particularly protection against copper corrosion, are imparted to the pneumatic tool lubricant of the invention by the incorporation of 0.05 to 0.2 weight percent mercaptobenzothiazole or a homolog thereof. The usual concentration of mercaptobenzothiazole is about 0.1 weight percent.

The pneumatic tool lubricants of the invention also advantageously contain a suitable amount of anti-foam agent since there is the possibility of air entrainment due to the high speed at which the pneumatic tools operate. For this purpose, a silicone polymer of high viscosity, such as dimethyl silicone polymer having a kinematic viscosity at C. of about 1,000 centistokes and above. is preferably employed, since this agent also desirably increases the fiash point of the fluid. A silicone polymer is conveniently employed in the form of a concentrate in a hydrocarbon solvent such as kerosene. For example, a very satisfactory anti-foam agent for this purpose is prepared by diluting 10 grams of a dimethyl silicone polymer (1,000 centistokes at 25 C.) with kerosene to bring the volume to cubic centimeters. A proportion of the order of 0.001 to 0.025 percent by weight of the foregoing concentrate is ordinarily employed which amount is sufficient to provide about 5 to 200 parts per million of the silicone polymer concentrate on the basis of the pneumatic tool lubricant.

We have found that lubricants of the above composition emulsify readily with water to form emulsions of good lubricating properties and in addition they are characterized by high load carrying and other properties, such as adhcsiveness, oiliness, etc., necessary to maintain good lubrication under the severe conditions encountered in rock drilling, including high loads, rapid mechanical jarring, impingement of high velocity gases and large temperature variations. They have the further advantage of being obtained from relatively inexpensive and readily available materials and are substantially free from objectionable odor.

The preparation of the novel pneumatic tool lubricants of this invention is illustrated in the following examples:

EXAMPLE I To a reaction vessel there were charged 2885.5 grams of a heavy naphthene base distillate oil having an SUS viscosity at 100 F. of 1625 and 2310 grams of a naphthene base distillate oil having an SUS viscosity at 100 F. of 208, and 6 grams of mercaptobenzothiazole. After the mixture had been raised with stirring to a temperature of 300 F., 18 grams of sulfur were added and the mixture stirred at a temperature between 290 and 300 F. for hour. 693.7 grams of a concentrate comprising about 63 weight percent of naphthene base oil having an SUS viscosity at 100 F. of about 70 and 37 weight percent of a high viscosity petrolatum oxidate having a Neut. N0. of 26, a Sap. No. of 126 and an SUS viscosity at 210 F. of 6,000 was added with stirring. The reaction mixture was then cooled to a temperature of F. at which temperature 19.8 grams of isobutylene polymer having a Saybolt Furol viscosity at 210 F. of 1400 seconds was added. Subsequently, 75 grams of a light naphthene base distillate oil containing 30 weight percent sodium sulfonate was added followed by 1 drop of a kerosene concentrate containing 10 percent of a dimethyl silicone polymer. The resulting product was a light red colored oil with mineral oil odor and had the following composition:

Mineral oil "percent by wt 94.59 Petrolatum oxidate do- 4.3 Sulfur do 0.3 Sodium sulfonate .d0 0.38 Isobutylene polymer do 4.33 Mercaptobenzothiazole do 0.1 Kerosene concentrate of dimethyl silicone p.p.m. 10

EXAMPLE II Another lubricant was prepared with the same ingredients and by the same procedure outlined in Example I with the sole exception being that the sulfur content was raised to 0.4 weight percent. The composition of this product was as follows:

Mineral oil percent by weight 94.49 Petrolatum oxidate do- 4.3 Sulfur do 04 Sodium sulfonate do 0.38 Isobutylene polymer do 0.33 Mercaptobenzothiazole do 0.1

Kerosene concentrate of dimethyl silicone p.p.m. 10

A field test batch of the pneumatic tool lubricant of the composition described in Example I was prepared by the following procedure: 176 pounds of naphthene base distillate oil having an SUS viscosity at 100 F. of 208 was charged to a reaction vessel together with 0.85 pound of mercaptobenzothiazole. After the reaction mixture had been mixed with stirring to 300 F., 2.55 pounds of sulfur was added and the mixture maintained between 295 and 305 F. with stirring for a half hour. 97.75 pounds of petrolatum oxidate concentrate having the composition set forth in Example I were added and the reaction mixture cooled with stirring. At about 140 F., 10.63 pounds of a light naphthene base oil containing 30 weight percent sodium sulfonate, 2.81 pounds of isobutylene polymer, 144.4 pounds of naphthene base distillate oil having an SUS viscosity at 100 F. of 208 and 415 pounds of naphthene base distillate having an SUS viscosity at 100 F. of about 1634 were added with stirring. 3.86 grams of the kerosene concentrate containing dimethyl silicone polymer was also added. The resulting product, which was a dark red oil with a mineral oil odor, had the same composition as the laboratory batch prepared in Example I.

EXAMPLE IV To a reaction vessel there were charged 7000 grams of a heavy naphthene base distillate oil having an SUS viscosity at 100 F. of 1625 and 2398 grams of a naphthene base oil having an SUS viscosity at 100 F. of 208 and 12 grams of mercaptobenzothiazole. After the reaction mixture had been heated with stirring to 300 F. there were added 2400 grams of a filtered sulfurized petrolatum oxidate concentrate prepared by the following procedure: A petrolatum oxidate having an SUS viscosity at 210 F. of 6000 was sulfurized at 350 F. for 4 hours with 7 weight percent sulfur; the resulting sulfurized oxidate having a total sulfur content of 6.63 weight percent and an SUS viscosity at 210 F. of 2345 was then dissolved by heating to 175 F. with stirring in a naphthene base oil having an SUS viscosity at 100 F. of about 75 in an amount sufiicient to form a concentrate. After cooling and settling, the concentrate was filtered.

Following the addition of the 20% concentrate of sulfurized petrolatum oxidate, 150 grams of a light naphthene base oil containing weight percent sodium sulfonate, grams of isobutylene polymer employed in Example I and 6 drops of the 10% kerosene concentrate of dimethyl silicone polymer were added. Stirring of the mixture was continued until a homogeneous product was obtained. The finished product had the following composition:

Kerosene concentrate of dimethyl silicone p.p.m. 10

A rock drill lubricant was prepared by a procedure similar to that outlined in Example IV employing a concentrate of a sulfurized low viscosity petrolatum oxidate. The petrolatum oxidate which was sulfurized at a temperature of 350 F. with about 7 weight percent sulfur had an SUS viscosity at 210 F. about 610, a Neut. N0. of about 10 and a Sap. No. of 82. The rock drill lubricant prepared employing the sulfurized low viscosity petrolatum oxidate concentrate was inferior in emulsification properties and rust protection as measured by the Humidity Cabinet Test to the rock drill lubricants of EX- amples I to IV based on the high viscosity petrolatum oxidates. The BF. properties of the rock drill lubricant formulated with the sulfurized low viscosity petrolatum oxidate concentrate as measured by the SAE Test at 500 rpm. were substantially equivalent to. those of the rock drill lubricants based on the high viscosity petrolatum oxidates. The superior anti-rust and emulsification properties of the lubricants based on the high viscosity petrolatum oxidates resulted in their selection for field trial evaluation.

The properties of products prepared in Examples I to IV are shown in the following table:

Table I.-Perf0rma'nce tests on pneumatic tool lubricants Evarn- Exam- Exam- Eample I ple II ple III ple IV SAE, 500 r.p.m 271 280 280 219 Almen Value, Avg. 35+ 35+ 35+ Navy Gear Wear, W. Loss/ 10,000 Cycles 4. 4 5. 3 10%? Humidity Cabinet, Hrs. to

Sandblasted 144 216 240 315 168 144 240 744 going performance tests, the product prepared in Example III was field tested with the following outstanding results: At one location a Gardner-Denver 4%" diameter drill, which operates at very high rotational speeds, was lubricated with excellent results for a period of more than 4 months with the rock drill lubricant of Example III. At another location, 8 drills of varying manufacture (Ingersoll Rand, Gardner-Denver and Chicago Pneumatic) employed in an iron mine were lubricated with the rock drill lubricant of Example III and provided excellent lubrication. The excellent rust protection provided by the rock drill lubricant of the invention was strikingly demonstrated by the fact that one of the drills lubricated with the product shown in Example 111 was in excellent condition even after it had been left idle for 5 weeks in a wet underground ditch containing highly corrosive water. In these field trials the rock drill lubricant of the invention was judged to give superior performance to competitive products and to the sulfurized lard oil based lubricant disclosed in the aforeidentified Bright and Hall patent.

Obviously, many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A pneumatic tool lubricant consisting essentially of a mineral lubricating oil having an SUS viscosity in the range of about to 900 at 100 F., containing 2 to 8 weight percent of a high ester content petrolatum oxidate characterized by a Neut. No. to Sap. No. ratio below about 0.25, 0.1 to 1 weight percent sulfur dispersed in a mixture of said mineral oil and petrolatum oxidate, and 0.1 to 0.8 weight percent alkali metal sulfonate.

2. The pneumatic tool lubricant of claim 1 in which said petrolatum oxidate is of the high viscosity type characterized by an SUS viscosity at 210 F. between 4,000 and 12,000.

3. The pneumatic tool lubricant of claim 1 in which said petrolatum oxidate is of the low viscosity type characterized by an SUS viscosity at 210 F. between 400 and 700.

4. The pneumatic tool lubricant of claim 1 containing 3 to 6 weight percent petrolatum oxidate, 0.3 to 0.7 weight percent sulfur and 0.2 to 0.6 weight percent sodium petroleum sulfonate.

5. A pneumatic tool lubricant consisting essentially of a mineral lubricating oil having an SUS viscosity at 100 F. in the range of from about 300 to 700 containing 2 to 8 weight percent of a petrolatum oxidate characterized by a Neut. No. to Sap. No. ratio below about 0.25, 0.1 to 1 percent sulfur said lubricating oil, petrolatum oxidate, and sulfur being blended into a homogeneous mixture by heating at a temperature between 250 and 350 F. for a period of about 30 minutes, 0.1 to 0.8 weight percent alkali metal sulfonate, 0.1 to 3.0 weight percent of a high molecular weight polymeric stringiness agent selected from the class consisting of olefin polymers, vinyl ether polymers and polymers of substituted fatty acid, said stringiness agent having a Saybolt Furol viscosity at 210 F. of about 1,000 to 2,000, and 0.05 to 0.2 weight percent of a mercaptobenzothiazole corrosion inhibitor.

6. The pneumatic tool lubricant of claim in which said petrolatum oxidate is of the high viscosity type characterized by an SUS viscosity at 210 F. between 4,000 and 12,000.

7. The pneumatic tool lubricant of claim 5 containing 0.3 to 0.7 weight percent sulfur, 0.2 to 0.6 weight percent alkali metal petroleum sulfonate and 0.1 Weight percent mercaptobenzothiazole.

8. The pneumatic tool lubricant of claim 5 in which said petrolatum oxidate is of the low viscosity type characterized by an SUS viscosity at 210 F. between 400 and 700.

9. A pneumatic tool lubricant consisting essentially of a mineral lubricating oil having an SUS viscosity at 100 F. in the range of 300 to 700 containing 3 to 6 weight percent petrolatum oxidate characterized by a Neut. No. to Sap. No. ratio below about 0.25 and an SUS viscosity at 210 F. above about 1500, 0.3 to 0.7 weight percent sulfur dispersed in a mixture of said mineral oil and petrolatum oxidate, 0.2 to 0.6 weight percent sodium petroleum sulfonate, 0.1 to 3.0 weight percent isobutylene polymer having a Saybolt Furol viscosity at 210 F. of about 1,000 to 2,000 seconds and 0.05 to 0.2 weight percent mercaptobenzothiazole corrosion inhibitor.

10. A pneumatic tool lubricant consisting essentially of a mineral lubricating oil having an SUS viscosity at F. between 100 and 900, containing 2-8 weight percent sulfurized petrolatum oxidate having a sulfur content of about 67 weight percent, said petrolatum oxidate being characterized by a Neut. No. to Sap. No. ratio below about 0.25 prior to sulfurization, and 0.1 to 0.8 weight percent alkali metal sulfonate.

References Cited in the file of this patent UNITED STATES PATENTS 1,913,300 Abrams June 6, 1933 1,987,397 Gallsworthy Jan. 8, 1935 2,349,224 Nill May 16, 1944 2,533,700 Wallace Dec. 12, 1950 2,638,446 Wasson May 12, 1953 2,655,478 Deutser et a1. Oct. 13, 1953 2,669,560 Sperry Feb. 16, 1954 2,705,241 McKinley et a1. Mar. 29, 1955 2,734,868 Bright Feb. 14, 1956 2,744,083 Moody et a1. May 1, 1956 2,764,547 Fields Sept. 25, 1956 FOREIGN PATENTS 616,881 Great Britain Jan. 28, 1949 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pete'it No 3,918,430 D b 2 1959 Melvin E, G'ililla'nd et a1,

It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 121,, line 58, should read as shown below instead of as in the patent iljsobutylene polymer do O Signed and sealed this 31st day of Nay 1960.,

(SEAL) Attest:

ROBERT C. WATSON KARL H AXLINE Commissioner of Patents Attesting Officer 

1. A PNEUMATIC TOOL LUBRICANT CONSISTING ESSENTIALLY OF A MINERAL LUBRICATING OIL HAVING AN SUS VISCOSITY IN THE RANGE OF ABOUT 100 TO 900 AT 100*F., CONTAINING 2 TO 8 WEIGHT PERCENT OF A HIGH ESTER CONTENT PETROLATUM OXIDATE CHARACTERIZED BY A NEUT. NO. TO SAP. NO. RATIO BELOW ABOUT 0.25, 0.1 TO 1 WEIGHT PERCENT SULFUR DISPERSED IN A MIXTURE OF SAID MINERAL OIL AND PETROLATUM OXIDATE, AND 0.1 TO 0.8 WEIGHT PERCENT ALKALI METAL SULFONATE. 